Field of the Invention
The present invention relates to mobile communications, and more particularly, to a technique for displaying a terminal existing within a coverage of an isolated E-UTRAN in an isolated E-UTRAN scenario in which a connection with an evolved packet core (EPC) is disconnected.
Related Art
In mission critical networks, it is very important to ensure communication functionality of public safety managers. An isolated E-UTRAN implies an E-UTRAN without normal connectivity with an evolved packet core (EPC) or a nomadic eNB (NeNB) with E-UTRAN functionality. The NeNB is a nomadic cell, and may consist of an eNB, an antenna, and a microwave backhaul. The NeNB is used to provide a service coverage or a additional capacity in public safety.
An isolated E-UTRAN operation is used when a normal backhaul connection is limited. This is for allowing the E-UTRAN to operate in an isolated manner without backhaul connectivity so that the communication functionality is provided between the public safety managers even if a user moves to outside an E-UTRAN coverage or there is a loss in a backhaul communication path. The isolated E-UTRAN operation aims to adapt to the failure and maintain an acceptable service level of a network in the isolated E-URAN. A service restoration is an eventual goal.
An evolved packet core (EPC) refers to a core network structure in a 3GPP long term evolution (LTE) network. The EPC has a form evolved from a GPRS core network, and consists of elements such as a mobility management entity (MME), a serving gateway (S-GW), a PDN gateway (P-GW), a home subscriber server (HSS), or the like.